Opening statements are expected today in the trial of a U.S. soldier charged with being the ringleader of a plot to murder Afghan civilians for sport.

Sgt. Calvin Gibbs of Billings, Montana is among five soldiers from the Army's Joint Base Lewis-McChord charged with taking part in three thrill kills in Afghanistan in 2010 in a case that includes allegations of widespread drug use, the collection of body parts and photos of the U.S. soldiers holding the Afghan bodies like hunter's trophies.

Three soldiers have already pled guilty. Gibbs, the squad leader, is accused of masterminding the murders, in which the soldiers allegedly set up scenarios to kill unarmed civilians and then planted weapons to make the deaths appear justified. He could face life in prison if convicted. Jury selection in the trial, which is being held in a military courtroom south of Seattle, began Friday.

In a confession taped in May 2010 and obtained by ABC News, one of the soldiers admitted the team's role in the murders, but told Army investigators that Gibbs, his unit's "crazy" sergeant, had hatched the plan.

"He just really doesn't have any problems with f---ing killing these people," Jeremy Morlock told military investigators during an interview videotaped at Kandahar Airfield, Afghanistan as he laid out the scenario he said the sergeant used to make it seem the civilians were killed in action.

"And so we identify a guy. Gibbs makes a comment, like, you know, you guys wanna wax this guy or what?" Morlock said." And you know, he set it up, like, he grabbed the dude."

Morlock said that killing people came "too easy" to Gibbs.

The corporal said Gibbs gave orders to open fire on the civilian at the same time Gibbs threw a hand grenade at the victim.

"He pulled out one of his grenades, an American grenade, you know, popped it, throws it, tells me where to go to whack this guy, kill this guy, kill this guy," Morlock told the investigators.

Morlock said Sergeant Gibbs carried a Russian grenade to throw next to the body of the dead Afghan, to make it seem he was about to attack the American soldiers.

The corporal said he opened fire as directed, fearful of not following Gibbs' orders.

"It's definitely not the right thing to do," Morlock told the investigators. "But I mean, when you got a squad leader bringing you into that, that type of real, that mindset, and he believes that you're on board with that, there's definitely no way you wanted him to think otherwise."

The investigator asked Morlock, "Because you felt maybe the next shot might be coming your way?"

"You never know. Exactly," answered Morlock. "I mean Gibbs talked about how easy it is, people disappear on the battlefield all the time."

A lawyer for Gibbs declined to comment. In March, Morlock pled to three counts of premeditated murder and was sentenced to 24 years in prison.

Holmes Kept Finger Bone from Victim

In September, Pfc. Andrew Holmes, of Boise, Idaho pled guilty to the unpremeditated murder of the first victim, as well as to drug use and to keeping a finger bone from the victim as a souvenir. Holmes had also posed for a photo, later leaked to the media, in which he held up the head of the dead victim.

Holmes, 21, admitted to the judge that he had fired his machine gun at the victim, that he knew the man was probably innocent , and that he believed he had caused the man's death.

Spc. Adam Winfield, who warned his parents that soldiers in his unit were executing innocent Afghan civilians, pled guilty in August to reduced charges and was sentenced to three years in prison for his role in the third killing, which took place in May 2010. He had been charged with premeditated murder, which carries a sentence of life in prison without parole.

Both Morlock and Winfield are expected to testify against Gibbs. Both have told Army investigators that Gibbs developed and rehearsed the murder of unarmed Afghans and later ordered his men to help him carry them out.

Spc. Michael S. Wagnon II, who is still awaiting trial, has pled not guilty. Wagnon is charged with participating in a cover-up of the second killing, which occurred in February 2010, as well as conspiracy and possessing a human skull fragment.

Lawyers for Gibbs and Wagnon have previously assailed Morlock's testimony against their clients, noting he requested investigative documents prior to testimony.

In addition to murder, the Army's charging documents allege rampant drug use in Morlock's unit, as well as the dismemberment of dead Afghan civilians.

Cpl. Morlock described in the Army investigators' video how Sergeant Gibbs allegedly collected the fingers of some of his Afghan victims.

Morlock said Gibbs boasted of carrying out similar murders in Iraq but was never caught and threatened the men in his unit with harm if they refused to participate or revealed what was happening.

"If Gibbs knew that I was sitting in front of this camera right now, there's no doubt in my mind that he'd f---ing take me out if he had to," Morlock told the Army investigators.

Winfield Told Parents About Thrill Kill

When Winfield told his parents in February 2010 about one of the incidents via Facebook, he also told them, "I want to do something about it. The only problem is that I don't feel safe here telling anyone."

He said there was a rumor that he was going to talk and "the threats are already coming my way."

In Afghanistan, according to other soldiers, Gibbs was becoming suspicious of Winfield.

An Army investigator asked Cpl. Morlock during his taped confession if he thought Gibbs was serious about maybe having to "take out" Winfield.

"Oh, f___ yeah, for sure, definitely," answered Morlock.

"So you didn't take that as a joke," said the investigator, "or like maybe it was just bull____."

"[Gibbs] doesn't bulls____," said Morlock. "He doesn't need to."

Adam Winfield's parents claimed in an interview with ABC News that in February they warned the Army by phone that soldiers in their son's unit were thrill killing civilians. One of the murders with which Winfield and the other soldiers were charged took place after the calls.

After an internal investigation, the Army has issued a statement saying that the parents of a soldier charged with murdering unarmed Afghans never called the Army's inspector general. The Army acknowledges that Christopher and Emma Winfield did call several numbers at their son's Army base in the U.S., and had an extended conversation with someone at the base's command center, but says the Winfields failed to leave a message with the criminal investigations unit at the base.

"The Army takes very seriously recent media reporting in which the father of Spc. Adam Winfield said he alerted the Army to allegations of crimes by Soldiers deployed to Afghanistan," said the Army's statement. "We have not yet found any evidence to indicate Mr. Winfield called the office of the Army's Inspector General."

"We examined the phone records of the Winfield family, with their consent. Based on this examination we have determined that another federal agency's Inspector General was called by mistake."